To see grown men hold their heads in anguish and then speak angrily about how they felt let down tells us all we need to know about the use of Gary Haggarty, one time North Belfast UVF leader, as a supergrass.

To see grown men hold their heads in anguish and then speak angrily about how they felt let down tells us all we need to know about the use of Gary Haggarty, one time North Belfast UVF leader, as a supergrass.

Haggarty pleaded guilty to more than 200 crimes including five murders, five attempted murders, 23 conspiracies to murder and a whole litany of other terrorist crimes, as well as asking for another 300 offences to be taken into account.

He was sentenced to 35 years in jail but had the term reduced to six and a half for assisting police. That included giving more than 1,000 interviews to officers, running to 12,000 pages.

And yet, apart from one trial yet to be heard, the use of this former paid informer - he had worked for the police for 11 years - and the gathering of this information resulted in exactly no successful prosecutions.

While the judge said that Haggarty had given police an enormous amount of information, the reality is that none of it - apart from the case still to be heard - was worth the paper it was written on. The Prosecution Service decided not to proceed to trial against the men he informed against because there was no collaborating evidence and essentially his word could not be trusted.

Once again - and not unexpectedly - the supergrass, or assisting offender, system has failed to bring the guilty to justice. It has been used against both republican and loyalist terrorists in Northern Ireland for almost 40 years and has been discredited.

But what it did in this case was shine a light on the very murky dirty war of the Troubles. Haggarty and his cohorts, some of whom were also paid informers, carried out a wide range of terrorist offences, including murder.

The judge made it clear Haggarty had not owned up to police about his and others' offences to atone for those crimes, but as a matter of pragmatism. For him it was a good deal, even if he will ultimately have to flee to a new life abroad to avoid falling foul of his fellow terrorists.

Like the families of those bereaved by Haggarty and his UVF cohorts, many people will struggle to accept that running them as informers really balanced out the evil deeds they committed. Did the information he provided equal or better the crimes he was involved in or is it just the case that morality was definitely the loser in this balance of competing interests.